Multiply 10 1/4 inches by 1/12. To make it easier, turn 10 1/4 into a mixed number by multiplying the 10 and the 4 and adding it to the 1.
41/4 x 1/12 = 41/48 (prime)
Now multiply 8 by 1/12.
8/1 x 1/12 = 8/12 = 2/3
The new dimensions are 41/48 inches by 2/3 inches.